Overexpression of a cytosolic glyceraldehyde-3-phosphate dehydrogenase gene OsGAPC3 confers salt tolerance in rice

Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) is a highly conserved glycolytic enzyme that plays an important role in carbon economy. However, recent analyses of GAPDH demonstrate that GAPDH is a multifunctional protein that has roles in various cellular functions. In this study, three putative cytosolic GAPDH protein sequences (OsGAPC1-3) were identified from the rice (Oryza sativa) genome. The OsGAPC family has similar exon-intron structures. OsGAPCs transcripts were highly present in seedling shoots and roots, booting leaves, and flowers, but are at low levels in booting culms. Three OsGAPC genes are responsive to all the abiotic stresses including osmotic (20% PEG 6000), salt (200 mM NaCl), heat (42A degrees C), abscisic acid (50 mu M) and methyl viologen (50 mu M) treatments. Transient expression of GFP-OsGAPC3 fusion protein in onion epidermal cells revealed that OsGAPC3 was indeed a cytosolic protein. One of the representative OsGAPC genes, OsGAPC3, which was induced most significantly by salt stress, was over-expressed in japonica rice Zhonghua 11 under the control of a ubiquitin promoter. Transgenic rice plants overexpressing OsGAPC3 showed enhanced tolerance to salt stress. Furthermore, we found that OsGAPC3 could alleviate the salt toxicity through the regulation of hydrogen peroxide (H(2)O(2)) levels. Taken together, these results indicate that OsGAPC3 plays important roles in salt stress tolerance in rice.